A conventional encoder for a game machine, having for example a left lever unit (L lever) and right lever unit (R lever) for manipulation is described by reference to FIGS. 13 to 15.
FIG. 13 is a perspective view showing a conventional general manipulator for a game machine. In FIG. 13, a cross switch operator 2, and several pushbutton switch operators 3 are disposed side by side on the top of a long flat casing 1. On one side of the long flat casing 1, an L lever 4 and an R lever 5 are disposed side by side. The use of the aforementioned switches is explained below by way of example of a TV car race game. The cross switch operator 2 is used like the steering wheel of a car, the R lever 5 is the accelerator, and the L lever 4 is the brake. The pushbutton switch operators 3 are not used in this case, and hence description with respect to operators 3 is omitted herein.
To accelerate and decelerate the car realistically, the L lever 4 and R lever 5 must not only be on/off switches, but also analog input devices. When the L lever 4 or R lever 5 is not manipulated, it is maximally extended, and the brake and accelerator functions are, accordingly, not effective.
FIG. 14 is a partially cut-away perspective view as seen from the rear side of the R lever 5 of the manipulator for the game machine shown in FIG. 13. FIG. 15 is a waveform diagram of an output signal of the manipulator for the game machine shown in FIG. 13. In FIG. 14, a shaft 6 is inserted into the long flat casing 1. The R lever 5 is rotatably fitted to the shaft 6, and is biased by a return spring 7 so that the R lever 5 is fully popped-out or biased when not depressed.
The R lever 5 has a gear block 8 engaged with a gear 10 provided in the center of a rotary slit panel 9 having multiple radial slits. When the R lever 5 rotates, the rotary slit panel 9 rotates at a multiple number corresponding to the gear ratio of the gear block 8 and gear 10.
Straddling the rotary slit panel 9, two photo interrupters 11A, 11B are disposed. Depending on the rotation of the rotary slit panel 9, a phase difference signal occurs between signal A generated by the photo interrupter 11A and signal B generated by the photo interrupter 11B as shown in FIG. 15, thereby enabling detection of rotation direction and rotation angle.
In the prior art device of FIG. 14, the elements for determining the phase difference shown in FIG. 15 are the two photo interrupters 11A and 11B. However, adjustment and alignment of the configuration of the photo interrupters 11A, 11B within a specified error is complicated thereby adding to manufacturing costs.
Moreover, an analog input device employing photo interrupters has high material cost thereby further increasing the manufacturing cost thereof. To address the above-described problems, a contact type encoder has been proposed in an effort to reduce costs. However, miscounting tends to occur in such devices due to characteristic chattering of the contacts, and thus the contact type encoder cannot satisfy the requirements for a manipulator for a game machine.